Research And Analysis On The Overall Strength Of Ballast Water Pipe Support Of General Purpose FPSO

The universal floating production storage and offloading device(FPSO)has received widespread attention due to its adaptability to production operations in multiple deep water areas.As an important part of hull stability control,ballast water system is very densely arranged in the limited space inside the hull.The stress,vibration and water hammer effect of the structure will have an important impact on the strength of the piping system.At present,the strength performance analysis of pipeline systems often neglects the integrity between pipelines and supports,thereby reducing the calculation accuracy of pipeline system strength,which has a significant impact on the economic and reasonable design of pipeline systems and the safety and stability of later operation.Therefore,it is very important to fully consider the integrity of pipeline supports in the study of pipeline system strength.The main work of this article is as follows:(1)Analyzed the factors affecting the strength of the universal FPSO ballast water pipeline support.Elaborated on the stress composition,failure forms,and basic theories of pipeline vibration and water hammer effects.(2)Based on the theory of pipeline stress analysis,a CAESAR II numerical model for a deep-water universal FPSO ballast water system was constructed.The stress of the pipeline system under multiple operating conditions was numerically simulated,and the rationality of the selected ballast water network system model was demonstrated.The load conditions of typical pipeline sections were extracted.(3)Based on the finite element theory,the statics characteristics of typical pipe sections under the conditions of single support,double support and pipeline as a whole,and three supports and pipeline as a whole are calculated through numerical simulation.Analyzed the impact of pipeline support integrity on the stress and deformation of the pipeline system.(4)An analysis was conducted on the impact of the overall pipeline support on the strength of the pipeline system under dynamic loads.The system structure and the damped and undamped modes considering fluid structure coupling were calculated for both the overall pipeline support and the simplified support as a constraint;And based on the magnitude of the support reaction force on the pipeline system,the deformation of the pipeline system under two different forms of harmonic excitation in different directions was calculated.Analyzed the influence of pipeline support deformation on the dynamic characteristics of the pipeline system.(5)Based on the water hammer theory and the parameters of the ballast water pipe section,a simplified calculation model for water hammer pressure in the pipeline system was designed,which is easy to calculate.With the FPSO operating conditions as the boundary conditions,the ANSYS fluid structure coupling calculation method was used to calculate the water hammer pressure of the pipeline system when the support effect is not considered and the integrity of the pipeline support is considered.Based on the pressure of the water hammer and the deformation of the support,the buffering effect of the support on the water hammer of the pipeline system was analyzed considering the integrity of the pipeline support.